While not limited thereto in its utility, the present invention is particularly well suited for employment on rotary wing aircraft. Such aircraft presently employ, as their source of power, turboshaft, i.e., free turbine, engines. Such engines include a gas generator and a free turbine driven by the exhaust products of the gas generator but not mechanically coupled thereto. The load, which constitutes the main and tail rotors in a rotary wind aircraft environment, is mechanically coupled to the free turbine. Two principal types of engine failure in a rotary wing aircraft are gas generator "flame-out" and a mechanical failure in the drive train between the free turbine and rotors.
Prior art gas turbine engine failure detectors have the rather serious deficiency of requiring, in the case of a flame-out failure, several seconds before providing a warning. Thus, present flame-out detectors are typically responsive to the decay of the gas generator speed below a normal idle speed minimum. Present engine failure detectors do not provide the pilot of a rotary wing aircraft with a warning in the case of either a flame-out or break in the power train between the free turbine and rotors.